User:Mbvanleeuwen/MB-Aramid
Introduction
aromatic polyamide were first introduced in a commercial application in the early 1960s, with the meta-aramid fibre Nomex, by Dupont. Aramid fiber is a heat-resistant and strong synthetic fiber. The idea for this material was originally developed in the early 1960s by Monsanto. However, Monsanto did not further develop this material at that time, but that was done by Stephanie Kwolek in 1961 while working at DuPont and at the same time at Akzo nobel in the Netherlands. It is used in aerospace and military applications, for "bullet-proof" body armor fabric, and as an asbestos substitute.
A well-known type of aramid fiber (a para-aramid) is Twaron, created by Akzo Nobel but currently owned by the Teijin company and basically the same as Kevlar, owned by the Dupont company. An especially fire proof variant is meta-Aramid, like Nomex, created by DuPont or Teijinconex by Teijin.
Production
The Federal Trade Commission definition for aramid fiber is "A manufactured fiber in which the fiber-forming substance is a long-chain synthetic polyamide in which at least 85% of the amide linkages are attached directly to two aromatic rings."
Aramid fiber is produced by spinning a solid fiber from a liquid chemical blend. This relies on a co-solvent with an ionic component (calcium chloride) to occupy the hydrogen bonds of the amide groups, and an organic solvent (N-methyl pyrrolidone) to dissolve the aromatic polymer; prior to the invention of this process by Leo Vollbracht, working at the Dutch chemical firm Akzo Nobel, no practical means of dissolving the polymer was known. The use of this system led to a patent war between Akzo Nobel and Dupont.
Different kinds of Aramids
Beside meta aramids like Nomex, Teijin also developed other variations which belong to the aramid fiber range.
Aramid fiber characteristics
- sensitive to degradation from ultraviolet radiation
- good resistance to abrasion, organic solvents, and thermal degradation
- sensitive to moisture and salts
- nonconductive
- no melting point
- low flammability
- good fabric integrity at elevated temperatures
- para-aramid fibers such as Kevlar and Twaron, provide outstanding strength-to-weight properties, and have high tenacity, and high Young's modulus.
- difficult to dye - usually solution dyed[1]
- prone to static build-up unless finished[1]
Major industrial uses
- flame-resistant clothing
- protective clothing and helmets
- body armor, competing with PE based fiber products such as Dyneema and Spectra.
- composite materials
- asbestos replacement
- hot air filtration fabrics
- tire and mechanical rubber goods reinforcement
- ropes and cables
- sail cloth (not necessarily racing boat sails)
- sporting goods
- drumheads
- speaker woofers
- Boathull material
- Fiber reinforced concrete
- Pipes
- Recently in tennis strings, because of its extreme durability. Popular aramid kevlar strings are made by Ashaway and Prince tennis companies.